Merge pull request #5 from jakobbuis/patch-2

Add basic postgresql installation guidelines to database.md

Author: brian7704

docs/database.md

@@ -10,4 +10,57 @@ engines
 - Microsoft SQL Server
 - Oracle
 
-See [SQLAlchemy's documentation](https://docs.sqlalchemy.org/en/20/core/engines.html) for more details.
+See [SQLAlchemy's documentation](https://docs.sqlalchemy.org/en/20/core/engines.html) for more details.
+
+## PostgreSQL 
+*** 
+
+OpenTAKServer can be configured to use PostgreSQL as its database backend.
+
+### Prerequisites
+
+Before configuring OpenTAKServer to run on PostgreSQL, ensure you have:
+- The database CA certificate (if an SSL connection is desired or required)
+- Access to your PostgreSQL database with a typical database client
+- Database connection details (hostname, port, username, password)
+
+### Installation
+
+Install the required PostgreSQL adapter in OpenTAKServer: 
+
+```shell
+sudo apt-get install libpq-dev
+cd ~/.opentakserver_venv
+bin/pip install psycopg2
+```
+If `ssl_mode=required` is on, download the database CA certificate from your provider and place it in the `~/ots` directory. 
+
+Modify the settings in `~/ots/config.yml` to include:
+
+```yaml
+SQLALCHEMY_DATABASE_URI: postgresql://[user]:[password]@[hostname]:[port]/[database]?sslmode=require
+SQLALCHEMY_ENGINE_OPTIONS:
+  pool_pre_ping: true
+  connect_args:
+    sslmode: require
+    sslrootcert: database-ca.crt
+```
+
+Replace `[user]`, `[password]`, `[hostname]`, `[port]`, and `[database]` with your actual database connection details. You can leave `SQLALCHEMY_ENGINE_OPTIONS` as is if the database does not use an SSL connection. 
+
+### Troubleshooting
+OpenTAKServer does not produce detailed error reports when something is wrong with the configuration file or database. It's easier to temporarily turn the service off and run the program directly for debugging. 
+
+To get detailed feedback about connection issues, run OpenTAKServer directly instead of as a service:
+
+```shell
+sudo systemctl stop opentakserver.service
+~/.opentakserver_venv/bin/opentakserver
+```
+
+If you encounter schema permission issues, ensure the database user owns the `public` schema. You may need to recreate it with the correct ownership.
+
+Finally, stop the OTS process in the terminal (Ctrl+C) and restart the service:
+```shell
+sudo systemctl start opentakserver.service
+```